I want to replace the gate valves on my cd25 , can anyone tell me why using full port ball valves are not recamended for use on threw hulls ?
wfeaster1@aol.com
gate valves
Moderator: Jim Walsh
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Larry DeMers
Re: gate valves
Gate valves can jamb in place easily, and are not acceptable for boats. I wonder how they came to be on your boat in the first place? Ball valves have a declining performmance curve. That is they are great in the first year or so, but decline rapidly after that. The ball tends to allow crud to grow on the exposed areas of the ball. When you go to operate it, the crud buildup stops your movement, thus restricting the movement. So now, your valve is either not going to close all the way or not open all the way due to crud buildup. Now new crud will grow on the previously unexposed area and that will decrease the travel further.
Additionally, the marelon type have a nasty habit of becoming brittle over time. I have read of *many, many* cases of the marellon handle breaking off when someone operated it. This is not a good device for our boats. Stick with the tapered plug style as they can be cleaned and rebuilt seemingly forever.
Larry DeMers
s/v DeLaMer
Cape Dory 30
demers@sgi.com
Additionally, the marelon type have a nasty habit of becoming brittle over time. I have read of *many, many* cases of the marellon handle breaking off when someone operated it. This is not a good device for our boats. Stick with the tapered plug style as they can be cleaned and rebuilt seemingly forever.
Larry DeMers
s/v DeLaMer
Cape Dory 30
Brace Tallents wrote: I want to replace the gate valves on my cd25 , can anyone tell me why using full port ball valves are not recamended for use on threw hulls ?
demers@sgi.com
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Bill Bloxham
Re: ball valves
Some pluses & minuses on ball valves, which I have in my Ty:
Minus - They don't fit.
The thread on thru-hulls is a straight thread, and the thread on ball valves is a tapered thread. Although they can have the same thread size numbers, the ball valves are "NPT", which means they are tapered.
The thru-hulls are not. So the threads of the thru-hull are only the same size at one point in the taper of the ball valve. This is not the best of all mechanical connections. A heavy blow to the unit or vibration could unseat the ball valve, with awful consequences. Finaly, a ball valve unit on top of a thru-hull is about as tall as a seacock.
Plus - For the LOD we all bought, we got tiny boats with some very tiny interior spaces.
My Ty scupper settup is very limited in vertical space, and my use of 45 degree els off the thru-hull to the ball valve made use of a viable(I think) assumption. That assumptation is that in the space where the assembly is that there would be little danger of a hard blow or vibration. I believe you could say the same of some spaces under sinks, around heads or in any number of other spaces in the boat. I beleive one important thing to observe in doing something like this is to use teflon tape when making a seal and to tighten the ball valve snugly on the thru-hull without overtightening it.
Please note I am not advocating the use of ball valves for engine/genset connections, or units at the bottom of a locker where you can dump heavy stuff on them.
In the end, the one absolute thing you cannot do is depend on the device to save you from being unaware of conditions around you and being indifferent about the way you use the device. Be informed, plan and act accordingly.
Oh, and by the way, my estuary-bound boat (Barnaget Bay, NJ)has not had any scale, growth or anything else in 5 years. If you are concerned about something cloging the valve, try painting the chanel in the ball with a antifoulant. Same with the interior of the thru-hull. My ball valves are bronze bodys with chrome plated balls.
Bill
mmmmmmbill@aol.com
Minus - They don't fit.
The thread on thru-hulls is a straight thread, and the thread on ball valves is a tapered thread. Although they can have the same thread size numbers, the ball valves are "NPT", which means they are tapered.
The thru-hulls are not. So the threads of the thru-hull are only the same size at one point in the taper of the ball valve. This is not the best of all mechanical connections. A heavy blow to the unit or vibration could unseat the ball valve, with awful consequences. Finaly, a ball valve unit on top of a thru-hull is about as tall as a seacock.
Plus - For the LOD we all bought, we got tiny boats with some very tiny interior spaces.
My Ty scupper settup is very limited in vertical space, and my use of 45 degree els off the thru-hull to the ball valve made use of a viable(I think) assumption. That assumptation is that in the space where the assembly is that there would be little danger of a hard blow or vibration. I believe you could say the same of some spaces under sinks, around heads or in any number of other spaces in the boat. I beleive one important thing to observe in doing something like this is to use teflon tape when making a seal and to tighten the ball valve snugly on the thru-hull without overtightening it.
Please note I am not advocating the use of ball valves for engine/genset connections, or units at the bottom of a locker where you can dump heavy stuff on them.
In the end, the one absolute thing you cannot do is depend on the device to save you from being unaware of conditions around you and being indifferent about the way you use the device. Be informed, plan and act accordingly.
Oh, and by the way, my estuary-bound boat (Barnaget Bay, NJ)has not had any scale, growth or anything else in 5 years. If you are concerned about something cloging the valve, try painting the chanel in the ball with a antifoulant. Same with the interior of the thru-hull. My ball valves are bronze bodys with chrome plated balls.
Bill
mmmmmmbill@aol.com